1. Field of the Invention
The present invention relates to a semiconductor device to be mounted on a main circuit board and a process for manufacturing the same.
2. Description of the Related Art
One example known in the prior art of such a semiconductor device as described above is illustrated in FIG. 14.
In this semiconductor device, conductive inner bumps 20 of a smaller diameter, each projected from an electrode (not shown) provided on an active surface of a semiconductor chip 10, are electrically connected to connection terminals 32 provided on the upper surface of a sub-circuit board 30 having substantially the same size as that of the semiconductor chip 10. A gap between the semiconductor chip 10 and the sub-circuit board 30 is filled with underfiller 40 so that the semiconductor chip 10 is bonded to the sub-circuit board 30. Conductive pads 34 are provided on the lower surface of the sub-circuit board 30. The conductive pads 34 are electrically connected via circuit patterns (not shown) of the sub-circuit board 30 to connecting terminals 32 on the upper surface of the sub-circuit board 30. A conductive outer bump 60 of a larger diameter having a hemispherical shape is projected from each of the conductive pads 34 for the electrical connection to a connection terminal 52 on the upper surface of a main circuit board 50.
According to this semiconductor device, it is possible to electrically connect a plurality of electrodes of various kinds formed at a small pitch in the peripheral region of the active surface of the semiconductor chip 10, via the inner bumps 20 and the circuit patterns of the sub-circuit board 30, with a plurality of conductor pads 34 provided on the lower surface of the sub-circuit board 30 at a large pitch in a matrix manner. And, it is possible to replace a plurality of electrodes arranged at a small pitch in the peripheral region of the active surface of the semiconductor chip 10 for the electrical connection to the connection terminals 52 on the upper surface of the main circuit board 50, with the conductive pads 34 arranged at a large pitch on the lower surface of the sub-circuit board 30 in a matrix manner. Together therewith, it is also possible to electrically connect selected electrodes formed on the active surface of the semiconductor chip 10 to each other via circuit patterns of the sub-circuit board 30.
It is possible to form a generally semispherical outer bump 60 of a larger diameter on each of the conductive pads 34 arranged at a large pitch in a matrix manner or the like, while maintaining a predetermined distance from the other outer bump 60 to avoid the contact with the other outer bumps 60 formed on the adjacent conductor pads 34. Then the plurality of generally hemispherical outer bumps 60 of a larger diameter could be easily and assuredly electrically connected to the plurality of connection terminals 52 arranged on the upper surface of the main circuit board 50 at a larger pitch in a matrix manner or the like. Thus, it is possible to electrically connect the plurality of electrodes on the active surface of the semiconductor chip 10 to the respective connection terminals 52 on the upper surface of the main circuit board 50 corresponding thereto.
The above-described known semiconductor device, however, has a drawback in that the semiconductor chip 10 is mounted on the main circuit board 50 via the sub-circuit board 30 having a larger occupation volume, resulting in the increase in size of the semiconductor device.
Further, the production thereof is troublesome because the semiconductor chip 10 must be bonded to the circuit board 30 via the underfiller 40.
Also, since the sub-circuit board 30 is complicated in structure, the production cost of the semiconductor device increases.
An object of the present invention is to provide a semiconductor device capable of eliminating such a problem in the prior art, which has no sub-circuit board to minimize a size thereof and reduce the production cost, and a process for manufacturing the same.
According to the present invention, there is provided a semiconductor device comprising: a semiconductor chip having an electrode and also having an active surface covered with an insulating layer; a rewiring circuit formed on the insulating layer, the rewiring circuit electrically connected to the electrode; an inner bump formed on a conductive pad which is a part of the rewiring circuit; an insulating film attached to the rewiring circuit and a surface of the insulating layer at a peripheral portion of the rewiring circuit, the insulating film having a through hole into which the inner bump is inserted; and an outer bump superimposed on the inner bump in the through hole so as to project to an outside opposite to the semiconductor chip.
The through hole is tapered so that cross-section area thereof is gradually larger toward the outside.
The outer bump is made of an eutectic solder, such as composed of 63 weight % of Sn and 37 weight % of Pb.
According to another aspect of the present invention, there is provided a semiconductor device comprising; a semiconductor chip having an electrode and also having an active surface covered with an insulating layer; a rewiring circuit formed on the insulating layer, the rewiring circuit electrically connected to the electrode; a conductive pad formed as a part of the rewiring circuit; an insulating film attached to the rewiring circuit and a surface of the insulating layer at a peripheral portion of the rewiring circuit, the insulating film having a through hole so that the conductive pad is exposed in the through hole; and an outer bump superimposed on the conductive pad in the through hole so as to project to an outside opposite to the semiconductor chip.
According to still another aspect of the present invention, there is provided a process for manufacturing a semiconductor device, the process comprising the following steps of: covering an active surface of a semiconductor chip with an insulating layer; forming a rewiring circuit on the insulating layer so that the rewiring circuit is electrically connected to an electrode of the semiconductor chip; forming an inner bump of a high melting point material on a conductive pad which is a part of the rewiring circuit; attaching an insulating film to the rewiring circuit and a surface of the insulating layer at a peripheral portion of the rewiring circuit, the insulating film having a through hole into which the inner bump is inserted; and superimposing an outer bump on the inner bump in the through hole so as to project to an outside opposite to the semiconductor chip.
According to still another aspect of the present invention, there is provided a process for manufacturing a semiconductor device, the process comprising the following steps of: covering an active surface of a semiconductor chip with an insulating layer; forming a rewiring circuit on the insulating layer so that the rewiring circuit is electrically connected to an electrode of the semiconductor chip; forming a conductive pad formed as a part of the rewiring circuit; attaching an insulating film to the rewiring circuit and a surface of the insulating layer at a peripheral portion of the rewiring circuit, the insulating film having a through hole so that the conductive pad is exposed in the through hole; and superimposing an outer bump on the conductive pad in the through hole so as to project to an outside opposite to the semiconductor chip.